Every developer knows the drill.
You're deep in a debugging session. You need to quickly decode a Base64 string, or format a minified JSON blob so you can actually read it, or generate a UUID for a test fixture. You open a new tab, search for a tool, land on a site drowning in ads and cookie popups, paste your data in, copy the result, and switch back to your IDE.
Two minutes gone. Flow broken.
I did this dozens of times a day not only for the same but for many others. And one day I just decided — I'll build one place that has all of it.
What I Built
The Dev Tools Online is a free, browser-based collection of developer utilities. No login. No ads. No data sent to any server.
Some of the tools available:
JSON Formatter & Validator — paste minified JSON, get clean indented output instantly
Base64 Encoder/Decoder — including image to Base64 conversion
UUID Generator & Validator — v4 UUIDs, bulk generation, validation
JWT Decoder — inspect token headers and payloads without any server call
Regex Tester & Generator — test patterns with real-time match highlighting
SQL Formatter — clean up messy query dumps
Code Beautifier — HTML, CSS, and JavaScript formatting
CRON Expression Parser & Creator — finally understand what*/5 * * * *means- Password Generator & Strength Checker
Hash Generator (MD5, SHA-1, SHA-256)- DNS Lookup & WHOIS
- Timestamp Converter, Age Calculator, Unit Converter
- And about 40 more...
The One Thing I Cared Most About: Privacy
A lot of developer tools silently send your input to their servers. That's fine for formatting public JSON, but not when you're pasting JWT tokens, API keys, database connection strings, or proprietary code snippets.
Every single tool on The Dev Tools Online runs entirely in your browser. There's no backend processing your input. Your data never leaves your device.
I made this a non-negotiable from day one. It's why I built it myself instead of just bookmarking someone else's site.
A Few Things I Learned Building This
1. PHP is still great for simple, fast tool sites
I went with a plain PHP + vanilla JS stack. No framework overhead, no build steps, no Node modules folder weighing 300MB. Pages load fast, the codebase is easy to maintain, and deployment is just an GitHub Actions push. Sometimes boring technology is the right choice.
2. .htaccess rewrite rules are both powerful and terrifying
Getting clean URLs (/json_formatter instead of /json_formatter.php) while handling redirects, blocking sensitive directories, and managing cache headers — all in one file — taught me more about Apache than 3 years of casual use did.
3. Browser-based tools are harder to build than they look
When you can't offload anything to a server, you have to handle every edge case in JavaScript. Malformed JSON, circular references, files that are too large, encodings that break on emoji — all of it has to be caught and handled gracefully in the client. It's a fun constraint to work within.
4. Content matters as much as the tools themselves
I initially launched with just the tools and minimal descriptions. Traffic was near zero. I've since added proper documentation to each tool — real examples, use cases, common gotchas. The difference in engagement has been noticeable.
What's Coming Next
I'm actively working on:
- A diff checker improvement with side-by-side view
XML to JSON and YAML validator improvements- A curl command builder (something I personally need all the time)
- Better mobile experience on tool pages
Try It Out
If you're constantly switching tabs for simple dev tasks, give it a try: thedevtools.online
Everything is free. Nothing requires an account. And if a tool you need is missing, hit the Contact page and let me know — I genuinely read every message.
I'm Umadhar, a software developer from India. Happy to answer any questions in the comments about the build, the stack, or the tools themselves.
Tags: webdev, javascript, php, productivity, opensource
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